1. Field of the Invention
The present invention relates to the treatment of "Sticky Cotton" for the reduction of the stickiness on the cotton fibers and, in particular, to enzyme compositions and methods using such enzyme compositions for the treatment of "Sticky Cotton" fiber for achieving a reduction of the stickiness thereon.
2. Background of the Invention
"Sticky Cotton" is a term used to refer to cotton fiber that has thereon sticky sugar deposits excreted by certain insects (mainly sweet potato whitefly) which feed on cotton leaves above open balls. Sticky cotton causes severe problems during the milling of cotton. Sticky cotton is a problem faced by cotton growers all over the world. The sticky substance is called "honeydew" and a number of publications have described methods of detecting honeydew in cotton. A summary of these methods can be found in the recent publication by Hendrix et at. (1). The composition of honeydew is a complex mixture of mono-, di, trisaccharides and small amounts of protein and organic acids (2,3). Hendrix et al. (4) developed High Pressure Liquid Chromatography (HPLC) techniques to separate oligosaccharides of honeydew up to pentasaccharides. A typical composition of the honeydew produced by white flies is 29.5% oligosaccharides, 10.1% sucrose, 5.3% glucose, 11.7% fructose, and 43.1% trehalulose (5).
Honeydew on cotton makes it difficult to process the cotton in gins and textile mills. Furthermore, the presence of such honeydew enhances the microbial fermentation for fiberstraining fungi which greatly deleteriously effects the fiber quality of the cotton. In gins, sticky cotton interferes with trash removal and requires gin blades to be cleaned more frequently, slowing ginning operation. This can significantly reduce the plant productivity. In textile mills, honeydew interferes with the major processing steps including carding, drawing, roving and spinning operations. Because of the adaptation of high speed technology, sticky cotton is a major threat in cotton production in many countries and plays an important quality consideration in the textile industry.
There seems to be limited work reported in reducing the stickiness of infected cotton. Heating the sticky cotton to 130.degree.-140.degree. C. for a short time was reported to caramelize the sugars in honeydew to avoid stickiness during spinning (6). The application of a hydrocarbon and surfactant additive to the cotton was reported to eliminate the sticking problem in yarn manufacturing (7). Another approach has been reported to spray contaminated cotton bales with dilute solutions of ammonium hydroxide or ammonium nitrate to enhance microbial breakdown of the sugars in honeydew (3). By this treatment, very sticky cotton lost all stickiness after 95 days. Others have indicated the use of insecticides to control cotton stickiness (8.9). The use of a material called Tempanil, reported to contain glucose oxidase, applied to contaminated cotton was found to significantly decrease soluble sugars (10). The change in stickiness of the treated cotton was not mentioned. Tempanil consists of two parts: a powdered preparation of glucose oxidase and catalase; and, a second part which is a liquid composed of a mixture of non-ionic and anionic wetting agents.
From the literature it can be seen very little has been done in the area of using enzyme to hydrolyze honeydew, except for the use of glucose oxidase. However, glucose oxidase only converts glucose to gluconic acid, and is not active on the sugars which are known to contribute to the stickiness of the cotton.
The complex low molecular weight di- and tri-saccharides i.e. trehalulose and melezitose, contributing significantly to the stickiness of the contaminated cotton are resistant to the hydrolysis by the conventional carbohydrate hydrolysing enzymes. These sugars contain simple sugars, glucose and fructose linked by alpha and beta glucosidic linkages. The structure of trehalulose and melezitose is given below.
(1) Trehalulose (O-.alpha.-D-glucopyranosyl-(1.fwdarw.1)-D-fructofruanoside) ##STR1## (2) Melezitose (O-.alpha.-D-glucoprosyl-O-(1-2)-O.beta.-D-fructofuranosyl-(3-1)-.alpha.-D -glucopyronoside) ##STR2##
Accordingly, it can be seen that there remains a need to provide a composition, and in particular an enzyme composition, which is capable of hydrolyzing honeydew on cotton fiber. It can further be seen that there also remains a need for a method for the use of such an enzyme composition for the treatment of such sticky cotton fiber in order to effect a reduction in the stickiness thereon.